Sound speed determination in copper shock compressed to 190 GPa

Journal Article · 23 October 2024 · Journal of Applied Physics

DOI: https://doi.org/10.1063/5.0220264 · OSTI ID:2473266

Hawreliak, J. A.  ^[1]; Winey, J. M.  ^[2]; Toyoda, Y.  ^[2]; Zimmerman, K.  ^[2]; Gupta, Y. M.  ^[2]

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1. Washington State University, Pullman, WA (United States); Institute of Shock Physics, Washington State University
2. Washington State University, Pullman, WA (United States)

Sound speed measurements in shock compressed solids have long been valuable for the development of equations of state at extreme conditions, shock-induced phase transformations, and a comprehensive characterization of the thermophysical response of high-pressure standards. We present results from plate impact experiments to 190 GPa to determine the longitudinal sound speed in copper—an important high-pressure standard. Surprisingly, the sound speeds determined using the two most common experimental techniques—the front surface impact (FSI) approach and the release wave overtake (RWO) approach—diverge significantly for stresses greater than ~100 GPa. Further analyses, including numerical simulations, show that the FSI experiments provide the correct sound speeds and that fundamental assumptions underlying the RWO method are likely violated due to the complex release response of shock compressed copper. The sound speeds determined using the FSI approach provide for a more accurate high-pressure description of copper in dynamic compression experiments. The present findings are in contrast to the results for shock compressed silver [Wallace et al., Phys. Rev. B 104, 214106 (2021)], where both methods provided consistent sound speed results. Thus, the findings presented here demonstrate the need to experimentally verify the validity of the RWO method on a case-by-case basis. Finally, we note that even at the high stresses in the present work, the copper unloading response shows a time-dependent, quasielastic response often observed in metals at lower stresses.

• Research Organization: Washington State University, Pullman, WA (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA), Office of Defense Programs (DP)
• Grant/Contract Number: NA0003957
• OSTI ID: 2473266
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 16 Vol. 136; ISSN 0021-8979
• Publisher: American Institute of Physics (AIP)Copyright Statement
• Country of Publication: United States
• Language: English